The present invention relates generally to guidewires for catheters and the like, and more particularly to a guidewire for use in a percutaneous transluminal coronary angioplasty procedure.
Medical catheters generally comprise elongate tube-like members which may be inserted into the body, either percutaneously or via a body orifice, for any of a wide variety of diagnostic or therapeutic purposes. Such medical applications frequently require use of a guidewire to facilitate the placement of catheters in the arterial system and other body lumen of a patient, particularly with regard to certain cardiovascular applications.
One such application requires manipulation of a guidewire from a position outside the patient's body through extended portions of the patient's arterial system to a position proximate a stenotic site. Stenosis is an abnormal narrowing of a passage or canal in the body, commonly associated with atherosclerosis, or blocking of the arteries with plaque. A balloon dilatation catheter is then mounted over the guidewire and advanced to the treatment site. The procedure expands intravascular lesions of soft or hard thrombotic or atheromatous material and is more formally known as Percutaneous Transluminal Coronary Angioplasty (PTCA). In a typical PTCA procedure, the guidewire is percutaneously inserted into the brachial or the femoral artery, and transluminally advanced to the stenotic region of the coronary artery.
Once a guidewire has been placed across a stenosis in the artery, the balloon catheter or other treatment or diagnostic catheter is advanced along or over the guidewire to the treatment site. On occasion, the treatment or diagnostic catheter is advantageously removed and replaced by a different catheter during the course of the procedure. In order to ensure that the guidewire is not dislodged from its position in the artery during removal of the catheter, the proximal portion of the guidewire extending out of the patient must be sufficiently longer than the overall length of the treatment catheter so that it can be firmly grasped throughout the removal of the treatment catheter. Conventional guidewires for use in PTCA applications are not long enough for this purpose.
Guidewires currently used for percutaneous transluminal coronary balloon angioplasty applications generally range in length from 100 to 200 cm with a typical dilatation catheter on the order of 130 to 145 cm long. Given the distance the guidewire must be inserted into the patient, the proximally projecting portion may be less than the length of the catheter.
Current guidewire extensions typically include some means for coupling an extension to a main guidewire to provide an added length over which to retract the catheter. One such device is shown in U.S. Pat. No. 4,966,163 to Kraus, et al. The device utilizes a combined extension and coupling member to ensure axial alignment with a main guidewire section yet allow rotational movement therebetween. The device disadvantageously requires a substantial amount of machining of the three independent mating parts.
Thus, there remains a need for a guidewire which is especially suited for procedures such as percutaneous transluminal coronary angioplasty possibly requiring a catheter replacement. In particular, the guidewire should be simply constructed and utilized such that catheters may be replaced without dislodging the guidewire.